Image encoding method of encoding a first image generated in accordance with image usage, and image decoding method of generating a second image by applying a filter selected based on image usage to the first image

An image encoder comprising:

• circuitry;
• and
• a memory connected to the circuitry,
• wherein, the circuitry, in operation:
• generates a first image by applying a prefilter to an input image in accordance with an image usage;
• and
• generates a bitstream by encoding the first image and information related to multiple first filters including the prefilter or a postfilter corresponding to the prefilter,
• the image usage includes at least one machine task and human vision which includes human viewing of video,
• the image usage is an image usage in an image decoder, and
• the circuitry transmits the bitstream to the image decoder.

An image decoding method comprising:

• acquiring a first image and information related to multiple first filters from a bitstream;
• selecting, based on information indicating an image usage, one first filter from the multiple first filters;
• and
• generating a second image by applying the one first filter to the first image,
• wherein the image usage includes at least one machine task and human vision which includes human viewing of video.

An image encoding method comprising:

• generating a first image by applying a prefilter to an input image in accordance with an image usage;
• and
• generating a bitstream by encoding the first image and information related to multiple first filters including the prefilter or a postfilter corresponding to the prefilter,
• wherein the image usage includes at least one machine task and human vision which includes human viewing of the video,
• the image usage is an image usage in an image decoder, and
• the image encoding method further comprising transmitting, by an image encoder, the bitstream to the image decoder.